Electronic switching system



Au'g. 28, 1945. c. c. sHuMARD ELECTRONIC SWITCHING SYSTEM origial Filed April 27, 195'? 2 Sheets-Sheet l INVENTOR.

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Aug. 28, 1945. c. c. SHUMARD ELECTRONIC SWITCHING SYSTEM 2 :aw o E *.v .....1f W m M e s. M i A a o h 8 7 1 T S 8 V l/ I T. .mm w 6 s f f Z w f w a w www fw i/mm 1, Wwf m a. .1 g 7 4 2 m n. llllllllllllll IIJ m WIL. n /70 .l P. vnv

Reiued Aeg.. 2s, 194s ELECTRONIC SWITCHING SYSTEM Charles C. Shumard, Moorestown, N. J., assigner of America, a corporation to Radio Corporatio oiwDelaware l Original No.

2,146,862fdated February 14, 1939, Serial No. 139,214, April 27, 1937. Application for reissue June 16, 1945, Serial No. 599,800

11 claims. (ci. 315-24) This invention relates to electronic switching devices and is more particularly concerned with an arrangement whereby it is possible to control two, three, four or more circuits in such manner that the transient or-other phenomena to be observed may, in eilect, -be simultaneously viewed on the luminescent screen of a cathode ray image producing tube. These patterns which are to be viewed are of the recurrent type and provisions are made according to the present; invention whereby a switch operation may take place at a frequency well above the frequency of persistence of vision so that by electrically controlling the rate at which the dierent recurrent wave forms are switched for operatively connected to one of the deflecting circuits of the cathode ray image producing tube, it is possible to view and compare, if desired, the various recurrent wave forms one with the other.

In an arrangement of this type the rate at which the different recurrent phenomena are to be observed Vand the rate at which the switching oi the application of the wave to one of the deflecting systems of the cathode ray image producing tube takes place is interlocked so that the directions along which the cathode ray beam is deiiected are mutually perpendicular. In practice, it is usually desirable to so connect and arrange the connections that the various recurrent phenomena which are to be observed shall be applied to the beam deflection control system of the cathode ray image producing tube as to deilect the cathode ray beam across the luminescent screen along the vertical path, while the time during which each phenomenon is applied or impressed upon the deflection control for ver# tical deiiection is coordinated with the rate at which the cathode ray beam is arranged to move ina substantially horizontal path from one edge of the luminescent screen to that edge opposite. 'I'his latter deiiection is generally known as the time sweep and 'provisions are made according to the present invention by which the ra-te or appli` cation of the phenomena is deiinitely interlocked with the time sweep of the cathode ray beam.

While it is usually preferable, as above stated, to'

apply the time sweep in the horizontal direction in contrast to the vertical, of course, it is to be understood that the invention, as it will be explained, is not in any way limited to this form of connection and may readily be applied in the opposite manner that is, for example, the time sweep applied in a vertical direction andthe recurrent phenomena applied in a horizontal direction.

. electronic According to the prior art various suggestions have been made. whereby a plurality of recurrent phenomena may, in eiect, be observed simultaneously upon the luminescent screen of a. cathode ray tube and the 'rate at which these observations are made to take place coordinate with the cathode ray beam deflection varied in accordance with time at some pre-established rate, it being understood that the time ci commencement of reproduction of the recurrent phenomena always commences at the same phasal position of the time sweep. It has already been suggested in the prior art t'oprovide switching arrangements of these general types and such switching arrangements while heretofore usually of the so-called mechanical type have also to a limited extent utilized purely A means. However, according to the prior art, these systems were more or less complicated and did-not in most instancesprovide for the rapidity of switching the rapidly triggering or flexibility of operation necessary where a great number of recurrent phenomena are to be simultaneously observed.

The present invention, therefore, has as its primary aim and object the provision of circuits which are extremely flexible in natureand which are readily adaptable to use for electronic switching for the simultaneous observation of recurrent phenomena where a numberof phenomena to be simultaneously observed shall be two, three,

four or any reasonably given number, the upper` determinable largely by limit, of course, being frequency limitations of the possibility of distinguishing each of the completelphenomenon with respect to each other in order that the desired comparisons may be made. Therefore, provisions are made according to the present invention by which the rapidity of switching between the several phenomena to be observed may be readily accomplished through the use of `grid controlled gaseous discharge tubes to which the recurrent phenomena to -be observed are applied and which become sequentially operative to impress the several phenomena in sequence upon one of the deflection circuits of the cathode ray tube.

Still other objects of the invention reside in the provision of circuits for accomplishing the switching of the connection to be observed in sequence to the deflection circuits in a manner which is relatively simple and free from unusual complications and which at the same time will involve 'a minimum amount oi equipment for utilization.

Still other objects and advantages of the invenber of switch electrodes 43, 44

tion win become apparent and at once suggest themselves to those skilled in the art to which the invention is directed by reading the iollowing specification and claims in connection with the accompanying drawings wherein;

Figure l represents schematically a three-circuit electronic switch o f thecathode4 shut-oi! typllgure 2 represents a modlneation of the arrangement of Fig. i applied to an increased numcircuits. and sh'ows particularlya modiiied form of cou Figure 3 represents still a further modification: and

Figure 4 shows a form of switching arrangement particularly adapted to switching under the control of alternating 'currents obtained div rectly from a power supply source.

Referring to Fig. l and assuming, for instance that three separate phenomena are to be observed; these transients or phenomenon may be impressed between a ground Il and the terminal points Il, I5 and I1 and capacity coupled by way of lcondensers I4, |115 to the control electrode of th'ree 2l and 23, suitable potentiometer connections are provided at 24, 28 and 2l. One end oi.' each potentiometer being connected to the input terminal the other end of each through a portion of a toone terminal of a between ground and a also connected in parallel with this path a second path comprising a condenser 33 and resistor 34 as connects to the supressor grid and th'e cathode of each of the amplifier tubes i9, 2| and 23. Y

While as shown each of these paths comprises potentiometers, condensers and resistances, it is. of course, to be understood that the values of these elements while usually made equal one to the other need not necessarily be so and the values assigned to the various elements of the circuit for convenience and for .the purpose of disclosing suitable values of resistance and capacity which have been found to be satisfactory may be varied within reasonable limits without departing from invention, the values being merely illustrative in nature and not in any sense limiting.

The output energy from the amplifying tubes I9, 2i and 23 respectively which have been supplied with plate voltage from a source connected between the ground II and a terminal point 31 by way of a resistor 38 are al1 connected in parallel by way of lthe conductor 39 and capacity coupled by way of the capacity and resistor combination 40, 4I to the input circuit of a common amplifying tube 42 whose output, as will be hereinafter explained, is applied across one pair of ing electrodes of a vided. The triggering operation is by controlling .the voltage vapplied accomplished to the screen and 45 of these tubes and this is of the tube 53, is a.

` 49, 5l and 53 connected at terminal point 54 and is an outer conductor 13 Referring now to the electronic switching circuit which shall place the several tubes I9, 2l and 2l in a state to become sequentially operative, a

way of the switch 55 and the 51 and all oi' thecathode electrodes connect to a ground point Il by way of resistor elements 52', and 5I. 'I'he conductors 45, "and 49 connect the screen electrodes 43, 44 and 45 of the tubes Il, 2l and 23 respectively to tubes 49, 5| and 53 and connect to the cathode electrodes 92, I3 and I4 of these last named tubes. The grid electrodes and 53 are supplied a source (not sh'own) connected between ground and the terminal point 98 and poled negatively with respect to 85 by connecting through to the conducting ring B9 by way of suitable resistor elements so that the grid is biased negatively relative to the cathode under conditions when switching or operativeness ot each individual tube does not take place. Connected to the grid electrodes of each of thetubes 49, 5| and 53 by way of condensers 1I). 1| and 12 which connects to a terminal point 14o! a second switch 15. Also connected directly to the grid of one o the tubes 49, 5I or 53, or as shown specifically to the grid second conductor 15 connected by way of a resistance 11 to terminal point 18 of the switch ann 19. Each of the switches 55, 15 and 19 is arranged to be operated in unison and to be switched between each of the three contact points shown so that in the position which the conductors 5l and switch 55 has been shown there is no connection between the source of plate voltage for the tubes the complete arrangement is in an inoperative state. Similarly, there is no connection established from the conducting member 13 to the terminal point 14 and the arm of the switch 15 but at this time there is established a connection between ground Il" and the terminal point 19 by vway of the arm of the switch 19 and th'e grid electrode of the tube 59. This connection preferably being made through the resistor 11 to a point on either side of the resistance 91.

Now to render the device operative the switches 55, 15 and 19 are moved in unison from th'e contact point at which the switch arms are shown to be resting .over to the next adjacent point.- this instance plate voltage will be applied to each of the tubes 49, 5I and 53 but there will be no connection established lbetween the conductor 13 and the arm o the Switch 15 although the consans nection between the ground point and the grid electrodes of each of these tubes by way of the contact point 18, the resistor 11 and conductor 18 is well established. The condition established by the switch resting in its median position in such manner as to connect ground through the switch 19 and-thereby Vconnect directly point. 18 through the resistance 11, conductor 18 to the grid 51 of the tube 53 produces a condition of un-symmetrical biasing of this grid with respect to the undisturbed bias existing on the grids 85 and 88 ofthe tubes 48 and 5|. In this manner the tube 53 is transferred for operation upon the simultaneous shifting of switches 85, 14 and 19 to the extreme right position. Moving now the switching arms so that each rests upon the terminal point furthest to the right from the position in which the switch arms are shown, it will be seen that plate voltage is still applied to the plate electrodes ol each of the tubes 49, and 53 but that now there has been established, by way of the arm of the switch 15, a connection from the conductor member 13 to the conductor 80 into which impulse switch circuit 8| by way of the potentiometer connection 82 shown as connecting with the cathode of the impulse developing tube 83 as will be hereinafter explained. But now the connection between ground Il" and the grid electrodes of each of the tubes 49, 5|Y and 53 has been broken.

In moving the switcharms from the position shown to the third position to athe right it. will be seen that the electronic switching device comprising the tubes 49, 5| and 53 is progresslvelyconditioned for operation because plate voltage is supplied. The bias for rendering the several tubes inoperative is applied so that the sequence of operation is determined by the unsymmetrical bias on the grid o! the tube 53. If now it is assumed that the switch arms have been moved to the furthest position to the right from that shown then it can be assumed, for instance, that the tube 53,' for example, isvv rst rendered operative to draw plate current. Thus immediately prior to this time there was applied to the gridy 68 of tube 5| and grid 85 of tube 49 a biasing voltage from the source connected to the terminal point 88 which was applied through resistors 85, 86 and 81 so that the tubes 5|. 49 are non-conducting. However, if tube 53 is rendered conducting then it will be appreciated that there occurs through the tube 53 and the resistor 8| connected between it and ground a voltage drop equal to the anode voltage connected between ground and the terminal point 54 for the several tubes 49, 5|, and 53. The usual voltage drop to be expected in a grid controlled gaseous discharge tube of the type of tube 53, hereinabove described and which, for example, may ibe of the type known in the art as the RCA885, is of the order of 16 volts. 4A suitable voltage for the source connected between ground and terminal point 54 is of the order of 116 volts'and therefore there occurs across the resistor 5I when tube 53 is drawing current,` a voltage drop of the order of 100 volts, assuming the values above suggested. This, therefore, carries the terminal pointof the resistorv 8| connected to the cathode B4 highly positive with respect to its previous condition andthere isapplied therefore through resistors 9|), 88, and 81, since tube 5| is not drawing grid current, a positive voltagel which opposes the voltage applied .between potentiometer ground and the terminal point 88 to bias the grid oi' the tube 5I, and the tube 48 then commences to draw plate current while the tube 53 ceases to draw plate current because the` potential of the cathode has` risen so high with respect to its previous state that it approaches the anode potential and the tube ceases to opperate. However, this operation is controlled more accurately as to time of occurrence by reason of the switch 15 being connected to the terminal point 14 and tothe condensers 12, 1|,and 18 and into the grid electrodes 81, 88 and 85 respectively of tubes 53, 5| and 48 which applies by virtue .of the operation ofthe discharge tube 83 forming a part of the impulse sweep circuit which changes the potential at the point at which conductor 8|| connected with the conductor 13 connects to the 82, so that there is, in effect, applied to the grid electrodes of the tubes 48, 5| and 58 an auxiliary impulse transferred by way o! the condensers 12, 1| and 18 and controls more accurately the time of operativer-less of the 'tube 5|. 'I'he triggering tube 83 is also of the grid controlled gaseous discharge type and serves to discharge the charge which has accumulated' erator '82 may be of the usual type and also comprises a condenser'charge'd from a. source of constant current and arranged to be discharged in Aaccordance with some suitable controlling impulse such, for example, as a recurrent 60 cycle signal or other frequency vsignal by way of either a so-called high vacuum discharge tube or another form of electronic discharge device such, for example, as a tube of the gaseous discharge type hereinabove described. Such sweep circuits are well known in the art and require -no further explanation being merely conventional in nature.

Whenever one of the tubes oi' the switching ring comprising tubes 49, 5| and 53 becomes operative and plate current is drawn from the' source connected between the ground and the terminal point 54, as was above explained, the potential of the cathode of the tube instantaneously operative rises with respect to the plate potential because of the fact that very little of the total voltage drop oi' the plate supplying voltage is impressed across the tube and therefore at this instant when any one of the tubes 49, 5| and 53 becomes operative by Way of connection of the conductor 48, for example, to the screen electrde 45 of the tube 23 and to the cathode 84kof the tube 53, the screenk electrode of the amplifier 23 is carried highlypositive after having been biased highly negative so that the tube by way of the conductor 13 cathode shut-oil' type by which'is meant described as soon as the tube Il has drawn plate current and at a frequency determined by the circuit constants that is, for example, the resistors 8l, 8l. I1 and particularly resistor 80 and condenser C, etc., and the frequency at which the discharge tube 88 operates and whose impulse is thereby impressed ,upon the grid electrodes 81 and the likel the several tubes Il, 48 and llet seq. are sequentially rendered operative. When the tube Il is next rendered operative following an operation of the tube I8 by which is meant the drawing of plate current, the tubes 28, 2| and i8 again are sequentially rendered operative and the phenomena impressed continuously upon the terminal points l1, I8 and il are sequentially applied to the deilecting plate electrode pair 88, 88 of the cathode ray tube 88.

While according iler tubes I8, 2| and 28 has been shown as being equal to the number of tubes 48, I8 and Il of the switching circuit, it is, of course, obvious that each of the tubes I8, 2| and 28 may be replaced by a pair of tubes connectedin push-pull whereby their inputs are balanced relative to ground in the usual manner. If now, for a further understanding oi' this disclosure, it is assumed that the tube Il is inoperative-then there is applied to the screen grid Il of the tube 28, for example, a biasing voltage which is determined by the resistance oi' the resistor 8| times the value of the biasing voltage negatively applied to the terminal 88 and between this terminal and ground all di- 2| and 28, there is applied to the trodes a negative bias which is removed in sequence as' the tube to whose cathode the screen grid is connected commences to draw plate current. Of course, under these conditions the biasing voltages on the screen electrodes of the tubes to Fig. lthe number of ampliscreen grid elec,

(that is operating) or s. non-conducting (that is biased or non-operating) condition.V In confor initiating the operation of any of the several .the selected frequency trast to the arrangement shown by Fig. 1 where the tube 83 was the iirst tube of the sequence to operate by the removal of the bias therefrom during the changing of the position of the switch 18. .provision is made for the use of a plurality of manuallyoperable switches |80, lll, |82 and |88 tubes |48, 48, 5I and Il respectively Ii' desired an attenuator |84 with suitable matching impedance may be used for supplying impulses from the sweep circuit 82 for initiating the operation, at

oi' the sweep circuit.

The power supply |10 purely of a conventional type with a good voltage regulation is arranged to supply operating voltages as was shown conventionally by the terminal point connections in Fig. 1. Throughout the remainder of Fig. 2 like parts olFig. 1 have been referred to by similar numerical indications and the additional tube necessary for the four-circuit switching has been referred to by numeral indications like the iirst tube but increased by one hundred.

In some instances it maybe desirable to trigger an electronic switch from an alternating current supply of yapproximately sinusoidal waveform. While this would not be the usual case since it is more frequently desirable to provide a triggering impulse of steep wave front, a sweep circuit may be synchronized from an A. C. supply source by providing an arrangement oi' the general type herein shown by Fig.'3. l

'Referring now to Fig. 3 the two tubes |18 and |18, each of which is preferably of the grid controlled gaseous discharge type. have their plate electrodes energized from a suitable source of alternating current input of an assumed voltage value e which is connected between the plate electrodes of the tubes |18 and |18 and a ground point |18. The cathodes of the tubes |18 and |18 also connect to this ground point, either di- |8, 2| and 28 are applied at all times except when one of these tubes is to be brought to an operative state and, in this event, the tubes are consecutively rendered operative by the removal of the biasing voltage and the application of a positive voltage tothe screen electrode to cause a rela tively heavy iiow o'f plate current.

Referring now to Fig. 2, there'is disclosed a'n arrangement for switching and supplying signals to the deflection plates of a cathode ray tube and shown by Fig. 1 insofar as it provides a common biasing source of energy foreach of the several tubes of the electronic switch comprising the tubes |48, 88, '5| and I8 and the control of the amplifying means is, as in Fig. 1, also of the that the control of the bias applied to the amplier tubes is dependent upon whether or not the tubes of the switching arrangement are in a rectly or through suitable resistors. 'I'he bias voltage |85 supplied between the grid |8| of the tube |18 and ground |18 is so adjusted that when the A. C. input supplied at vsource |16 reaches i a predetermined value the tube Ill/momentarily v ity of tube |18 conducting impulseA terminals |82 and |88.

becomes conducting with the result that a voltage drop takes place across the resistor |88 so that the terminal point or this resistor connected to the cathode of the tube |18 becomes highly positive relative to its previous condition and'approaches thepotential on i ie plate electrode of this tube. Due to the connection from the termi-- vnal oi resistor |88 connected to the cathode of tube |18 the grid electrode |80 of the tube |18 has its effective bias which has been supplied from the bias source |84 lowered by way of the connection through the condenser and the resistor |88 to the grid electrode |80 by the voltage drop taking place under conditions of conductivthrough resistor |88. Normally. the bias voltage |84 exceeds the voltage |88 but when the elfective bias applied to the grid |80 by the source |84 is lowered the tube |18 commences to conduct and draw current, and the tube |18 is substantially short-circuited. At this time the tube |18 is cut-oirv since only the'voltage drop oi tube |18 exists across the whole of the tube |18 shunt circuit.' Tube |18 will shut oil' shortly before the input voltage e supplied at4 I 18 goes negative. In this manner it will be seen that one impulse per cycle of input is obtained at the output In this arrangement the resistor |11 serves to limit the current through the tube |19 and also serves to provide regulation. The resistors |01 and |09 limit the grid current owing while the resistor lll serves as a coupling medium.. Ac-

cording to usual practice. the resistance |09 should usually be kept small and the resistors |11 and may be of the same order. In accordance with this arrangement the time constant of the impulse produced across the output terminals |22 and |02 by the connection made to the resistor |09 is approximately equal to the sum .of the resistance values |09 and |92 -times the capacity |90.

A still further modification of the invention as applied to a two-circuit switch and wherein the control is provided from an A. C. source, such as a 60 cycle supply, has been shown by Fig. 4. Reierring now to this modification of the invention the impresssed alternating currents used both for power supply and for controlling the switching time provided for the observation of the two phenomena supplied at the terminal points |9| and |92 are connected at terminals |90 for the purpose of controlling -this switching operation as well as for supplying through a suitable supply unit |92 operating voltages. The impressed alternating currents applied at the terminals |90 when used to control the operation of the switching of the impresssed phenomena appearing at the terminals |9|` and |92. the switching operation control from the lA. C. supply and permitting the observation of at least a full cycle of the switch signal, the frequency of the switching voltage should preferably be a maximum of one-quarter of the switch signal frequency, since the transient switching time is an appreciable part oi' a cycle. Since such a frequency is usually not available whereas the 60 cycle A. C. is readily obtainable from the power supply the arrangement of Fig. 4 is suitable for obtaining this frequency relationship.

The oscillator tubes |94 and |90 (preferably of the type known in the art as 2A3) are connected with the pla-te electrodes connecting to opposite end terminals of the primary of the transformer |99 which is center-tapped back to the cathode. The transformer primary is shunted by a condenser |91 and cross-connected between the grid of tube |94 and the plate of tube |95 is a connection including condenser |90 of which the terminal connected nearest to thegrid of tube |94 is connected by a resistor |99 back to the plate circuit. Similar connections including condenser I99' and resistor |99' are provided for tube |99.- In this arrangement the constants are preferably so chosen that the oscillator oscillates at an Iassumed frequency of l5 cycles, assuming the frequency oi the A. C. supply at terminals |90 to 'be 60 cycles.

A pair oi' `gaseous discharge tubes 200 and 20| of the grid controlled typey such for example as tubes known in the ar-t as the type 885, have their plate electrodes connected respectively to the end terminals of the secondary of transformer |90, across which is connected the condenser 202.

The phenomena applied at terminals |9| and |92 are supplied to the control electrode oi' tubes 203 and 204 respectively by way of the voltage dividers 205 and 208 and one of the grids 0f each of these tubes also connects withthe plate electrode of the tubes-20| and 202. The grids of tubes 209 and 204 are suitably biased as shown and plate potentials for these tubes are supplied from the power supply |92. By way oi' the con- For the purpose of providingl nection 201 from the cathode connection of tubes 200 and 20| the lvoltage drop from the plate to cathode of the tubes 200 and 20| may be utilised to bias the tubes 20| and 202 to control the operative periods of each. In accordance with the time periods when either of the tubes 200 or 20| is made conducting by virtue of the energy supplied at the terminal of the secondary of transformer |99 rising in the positive sense. either of the tubes 203 or 204 is positively biased and the signals impressed at the terminals lli and |92 are amplied and transferred by way o! the parallel output connection' 209 to the terminal points 2|0 and utilized either for the purpose of controlling the deflection of a cathode ray beam .or for the purpose of determining which of the plurality of impressed signals is effective in the load circuit connected with these terminals points.

The arrangement for applying the biasing voltages to the various grids of the tubes 203 and 200 are quite analogous to the arrangements already described and are not herein repeated again in detail. It will be seen that the resistors 2| I serve to limit the plate current flowing through the tubes 200 and 20| whereas the grid resistors 2|2 serve to limit the grid current. These values are not critical but by way of example may be of the order of 5000 to 15,000 ohms.

Referring now further to Figs. l and 2, it will be noted that in connection with Fig. 2 the impulse from the attenuator IBI is' applied across the resistor |93' through the condensers |90', when the switch 19 is on the contact furthest to the right but otherwise through the resistor |83" and the manual switches where resistor |93" is preferably made equal to the resistor |02'. This is in contrast to the arrangement of Fig. l where the impulse is applied only through the condensers 10, 1| and 12. With the arrangement of Fig. 2, the condensers are not absolutely essential but serve to decrease attenuation and the amount of impulse voltage required. Thus, at the higher frequencies the resistance ,|93' can be omitted and coupling established only by way oi' condensers |94', while at the lower frequencies only the resistance |83' need be used. It may be further worth noting that with the arrangement of Fig. 2, that where the resistance 80 is relatively small relative to resistances and 80, that the screen voltage on the tubes I9, 2|, etc., is su-bstantially zero..

While in connection with the showing of Fig. 1 various values suitable for the various resistance and capacity elements shown have been tabulated immediately beneath the figure of the drawings, these values have been given merely by way of example and are not -to be construed as limiting in any manner but rather as illustrative of one suitable set of operating constants. Further the general arrangement described by the several figures of the drawings herein, while having been illustrated, especially in connection with the simultaneous viewing of different patterns on a cathode ray tube screen, is in no sense limited to these applications. While it is not desired to speciilcally enumerate each of the possible uses of the invention, it might be pointed out that the amplier tubes I9, 2|, etc., associated with the switching` circuit, including the tubes 99, 5|, 53, etc., may be adjusted to supply from their plate mixing circuit stepped directcurrent voltages, either by adjusting each individual control grid bias, or by tapping the switch voltage for different screen-grid bias to each` amplifier tube. Further, by the use of the arrangement herein shown separate oscillators, amplifiers or other apparatus may be eifectively switched by electronically switching some controlling voltages so amplifying means to one that audio tones of different amplifiers. for exthe art and therefore it is desired that the disclosure be construed as covering all forms of switching systems which fall clearly within the spirit and scope of .the hereinafter appended claims.

l. An electronic switching device comprising a network including a plurality of electron tubes each having grid, cathode and anode electrodes, a common source of anode potential for all of said tubes, circuit connections including a plurality of resistance elements connecting the cathode electrode of each tube of the network to the grid of the next succeeding tube in the sequence and the grid of the last tube of the sequence to the cathode of the first tube of the sequence, a common source of voltage for supplying cut-off biasing potentials upon the grid electrodes of all of the tubes for normally maintaining the several tubes inoperative, switching means for reducing, upon starting, the biasing voltage on one of the tubes to a value to permit the tube to draw plate current, means for subsequently rendering the several'tubes in the sequence sequentially and consecutively operative following the initial operation of the nfst tube of the sequence, a plurality of sources of signal energy and amplifying means associated with each of the sources, a load circuit connected with the output of the amplifying means, means for` normally maintaining the amplifying means inoperative and means for rendering the amplifying means sequentially and consecutively operative at time periods of oper-v ation of the sequentially operating tubes to connect thereby the amplifying means to the load circuit.

2. An electronic switching device comprising a plurality of thermionic tubes arranged in a sequence, each of said tubes having grid. cathode and anode electrodes, a common source of anode potential for all of said tubes, a circuit comprising a plurality of resistance elements connecting the cathode of each of the tubes to the grid of the next succeeding tube in the sequence and the grid of the last tube of the sequence to the cathode of the iirst tube of the sequence, means for supplying cut-oil' biasing potentials upon the grid electrodes of all of the tubes, means for reducing, upon starting, the biasing voltage on one of the tubes to' a value to permit the tube to draw plate current, means for rendering the tubes in sequence sequentially operative following the initial operation of the first tube of the sequence, a. plurality of sources of signal energy and amplitying means associated with each of the sources, a control from each of the individual amplifying means to one of the said tubes of the ilrstnamelsequence whereby the amplifying means are rendered sequentially operative in accordancelwiththe operation of the tubes of the rstnamed sequence, a. common output connection for all of the amplifying means, and a load circuit for utilizing the output of the said amplifying means, said load circuit comprising a cathode ray tube having deflection circuits for deecting the developed cathode ray beam in a. plurality of mutually perpendicular directions, and means for naar:

supplyingthe output of the parallelly connected of the deilection circuits of the cathode ray tube. y

3. An electronic switching device comprising a plurality of thermionic tubes each having grid, cathode and anode electrodes and arranged to operate in a predetermined sequence, a common source of anode potential for all of said tubes, a

Vciruit comprising a plurality of resistance elements connecting the cathode of each of the tubesjto the grid of the next succeeding tube in sequence and the grid of the last tube of the sequence to the cathode of the first tube of the sequence, means for supplying cut-oil' biasing potentials upon the grid electrodes of all of the tubes for normally maintaining the tubes inoperative, means for reducing, upon starting, the biasing voltage on one of the tubes to a value to permit the tube 1to draw plate current, means for rendering the tubes in the sequence sequentially and consecutively operative following the initial operation of the nrst tube of the sequence, a plurality of sources of signal energy and amplifying means associated with each of the sources, a control from each of the ,individual amplifying means to one of the said tubes of the first named sequence for normally maintaining the amplifying tubes inoperative and means for rendering the amplifying means sequentially operative at time periods coinciding with the periods of operation of the tubes of the ilrst named sequence, a parallel output connection for all of the amplifying means, and a load circuit for utilizing the output of the said amplifying means.

4. An electronic switching device comprising a plurality of thermionic tubes each having grid, cathode and anode electrodes and arranged to operate in a predetermined sequence, a common source of anode potential for all of said tubes, a circuit comprising a plurality of resistance elements connecting the cathode of each of the tubes to the grid of the next succeeding tube in the sequence and thegrid of the last tube of the sequence to the cathode of the first tube of the sequence, means for supplying cut-off biasing potentials upon the grid electrodes of all of the tubes for normally maintaining the tubes inoperative, means for reducing, upon starting, the biasing voltage on one of the tubes to a value to permit the tube to draw plate current, means for rendering the tubes in the sequence sequentially and consecutively operative following the initial operation of the first tube of the sequence, a plurality of sources of signal energy and amplifying means associated with each of the sources, a control from each of the individual amplifying means to one ofthe said tubes of the rst named sequence for normally maintaining the amplifying tubes inoperative and means for rendering the amplifying means sequentially operative at time periods coinciding with the periods of operation of the tubes of the iirst named sequence, a paralle] output connection for all of the amplifying means, and av load circuit for utilizing the output of the said amplifying means, said load circuit comprising a cathode ray tube having deflection circuits for deecting the developed cathode ray beam in a plurality oi' mutually perpendicular directions, and means for supplying the output of the parallelly connectedamplifying means to one of the deflection circuits of the cathode ray tube.

5. 'I'he system claimed in claim 1 wherein said load circuit comprises a cathode ray tube, and means Afor supplying the output from the ampliiler to the cathode ray tube to deflect the cathode ray beam developed therein in one of two mutually perpendicular directions.

e. The system manned in claim 3 wherein said operative tubes and the deflection control means for interlocking the sequential operation and the deection control whereby the said tubes of the sequence are rendered sequentially operative at predetermined time periods in the deflection of a plurality of signal energy channels, a relay device connected with each signal channel, a load circuit connected to be energized from the relays. a `switching network including a plurality of electron tubes each having at least a control electrode. a cathode and an anode, a source of anode potential for all of said tubes, circuit connections including a plurality of impedance elements connecting the cathode electrode of each tube of the network to the control electrode to the next succeeding tube in the sequence and the control electrode of the last tube of the sequence to the cathode of the iirst tube of the sequence, means for supplying biasing potentials upon the control electrodes of all of the tubes for normally maintaining the several tubes in one of two equilibrium the cathode ray beam in the direction perpenv dicular to the direction of deflection provided by the parallelly connected outputs from the amplifying means.

8. A system claimed in claim 4 comprising, in addition, a sweep frequency generator for deflecting the cathode ray beam developed in the cathode ray tube in a direction perpendicular to the path of deilection initiated by the output of said parallelly connected amplifying means, and means interconnected between the sequentially operative tubes and the deection control means for interlocking the sequential operation and the deection control whereby the said tubes of the sequence are rendered sequentially operative at `predetermined timeperiods in the deflection of A the cathode ray beam in thedirectionperpendicular to the direction of deflection provided by the parallelly connected outputs from theamplifying-means. y

Ail. An electronic switching device comprising a network including a plurality of electron tubes each having at least a control electrode, a cathode and an anode, a source of anode potential for all of said tubes.` circuit connections including a plurality of impedance elements connectstates of operativeness. switching means for a1- tering. upon starting, the bias voltage on one of the tubes to a value to permit the tube to change to the other of the two equilibrium states of operativeness, means for subsequently changing the several tubes of the sequence to the last named equilibriumstate of operativeness sequentially following the initialchange in the operative state ing the cathode of each tube or the'network to the control electrode oi' the next succeeding tubev oi' the sequence and the control electrode of the lasttube of the sequence to the cathode of'the ilrst tube oi" the sequence, means for supplying cut-off biasing potentials upon the control electrodes of all of the tubes for normally maintaining the several tubes inoperative, switching means for altering, upon starting, the biasing voltage on one of the tubes to a value to permit the tube to draw current, means for subsequently rendering the several tubes in the sequence operative sequentially following the initial operation of the nrst tube of the sequence, a plurality of sources of signal energy and amplifying means associated with each of the sources. a load circuit connected with the output of the amplifying means, means for normally maintaining the amplifying means sequentially and Aconsecutively operative at time periods of operation oi' the sequentially operating tubes to connect thereby the amplifying means to the load circuit.

l0. An electronic switching system comprising of lthe rst tube of the sequence, means for normally maintaining each relay inoperative to energize its associated load circuit, and means provided by said switching network .for rendering the several relays operative in sequence to energize the load circuit in accordance with the presence and absence of signals upon the plurality of signal energy channels.

'11. An electronic switching system comprising a plurality of signal energy channels, a relay device connected with each signal channel. a. load circuit connected to be energized from said relays, a switching network including a plurality of electron tubes each having at least a control electrode, a cathode and an anode, a source of anode potential for all of said tubes, circuit connections for connecting the cathode circuit of each tube of `the network to the control electrode l circuit o f the next succeeding tube in the sequence and the control electrode-circuit oi! the last tube of the sequence to the cathode circuit ofthe first tube of the sequence, means for supplying biasing potentials of one polarity upon the control electrodes of all oi' the tubes for normally maintaining the several tubes' in one ofV two`equilibri`um states of operativeness, an impedance .element connected in each cathode circuit, switching means connected with the impedance elements for altering, upon starting, the voltage yon one of the-tubes to a value to permit the tube to change to the other ofthe two equilibrium states of operativeness, means for subsequently changv ing the several tubes of the sequence to the last named equilibrium state of operativeness'sequentially following the initial change in the operativel state of thenrst tube of the sequence, means for normally `maintaining each relay inoperative to energize itaassociated load circuit, and means provided by said switching network -i'or rendering the several relays operative in sequence to energize the load circuit in accordance with the presence and 'absence 'of signals upon the .plurality of signal energy channels.

- CHARLES c. sHUMAnD. 

